Amounts of substance

Question 1

What is the symbol for amount of substance

Answer 1

n

Question 2

What is the unit used to measure amount of substance

Answer 2

Mole

Question 3

What does Avogadro constant represent

Answer 3

the number of atoms per mole of carbon 12 isotope

Question 4

Equation for calculating moles

Answer 4

Moles = mass / mr

Question 5

State Avogadro’s law

Answer 5

Under the same temperature and pressure, one mole of any gas would occupy the same volume

Question 6

How much volume does a gas occupy at rtp

Answer 6

24 dm3

Question 7

Define molar gas volume

Answer 7

The volume per mole of gas molecules

Question 8

Why do different gas particles occupy the same volume

Answer 8

Gas particles are very spread out, so individual differences has no effect.

Question 9

How to calculate moles when gas volume is given

Answer 9

Moles = volume / 24

Question 10

What are the ideal ways in which gases behave

Answer 10

They are in continuous motion

No intermolecular forces experienced

Exert pressure when they collide

No kinetic energy is lost in collisions

Question 11

What is the ideal gas equation

Answer 11

Pv = nRT

Question 12

1 atmospheric pressure is equal to how many pascals

Answer 12

1 atm = 101325 PA

Question 13

0 degree Celsius is how many kelvin

Answer 13

273 K

Question 14

What does concentration of solution mean

Answer 14

Amount of solute dissolved in 1 dm3 of solvent

Question 15

Equation including moles, concentration and volume

Answer 15

Moles = conc * volume

Question 16

What is a standard solution

Answer 16

A solution of known concentration

Question 17

How do you prepare a standard solution

Answer 17

Weigh the solute using the weigh by difference method

In a beaker dissolve the solute using solvent

Pour the solution into a volumetric flask

Rinse the beaker using the solution and add it to the flask

Add solvent to flask carefully until it reaches the graduation line

Mix the solution thoroughly to ensure complete mixing

Question 18

What does concentrated mean

Answer 18

Large amount of solute per dm3 of solvent

Question 19

Define dilute

Answer 19

small amount of solute per dm3 of solvent

Question 20

What is species in a chemical reaction

Answer 20

Any particle that takes part in a reaction

Question 21

Define percentage yield

Answer 21

The efficiency of which reactants are converted into products

Question 22

What are reasons for not obtaining 100% yield

Answer 22

Side reactions may occur

Incomplete reactions

Reactants or products may be left behind

Reactants may be impure

Question 23

Formula for percentage yield

Answer 23

Percentage yield = actual amount / theoretical amount

Question 24

What does atom economy tell us

Answer 24

The proportion of desired products compared with all the products formed in the reaction

Question 25

Formula for atom economy

Answer 25

Atom economy = mr of desired product/ sum of mr of products

Question 26

Which type of reactions has 100% atom economy

Answer 26

Addition reactions